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Using Cyclone Devices in Multiple-Voltage Systems
To meet the demand for higher system speed in data communications,semiconductor vendors use increasingly advanced processingtechnologies requiring lower operating voltages. As a result, printedcircuit boards (PCBs) often incorporate devices conforming to one ofseveral voltage level I/O standards, such as 3.3-V, 2.5-V, 1.8-V and 1.5-V.A mixture of components with various voltage level I/O standards on asingle PCB is inevitable.In order to accommodate this mixture of devices on a single PCB, a devicethat can act as a bridge or interface between these devices is needed. TheCyclone® device family’s MultiVolt™ I/O operation capability meets theincreasing demand for compatibility with devices of different voltages.MultiVolt I/O operation separates the power supply voltage from theoutput voltage, enabling Cyclone devices to interoperate with otherdevices using different voltage levels on the same PCB.In addition to MultiVolt I/O operation, this chapter discusses severalother features that allow you to use Cyclone devices in multiple-voltagesystems without damaging the device or the system, including:■ Hot-Socketing—add and remove Cyclone devices to and from apowered-up system without affecting the device or system operation■ Power-Up Sequence flexibility—Cyclone devices can accommodateany possible power-up sequence■ Power-On Reset—Cyclone devices maintain a reset state untilvoltage is within operating range
